Honestly, what I'd love to see is a brand new Sim City with a more complex economy (goods, natural resources, etc). You could build your city around either some sort of resource gathering (mining, fishing, ...), industry (manufacturing, refining), or commerce, or a mix of them.
Then when you play multiplayer you can set up trade routes with other people's cities, 'borrow' electricity/water from your neighbors, or whatever. And if a city positioned directly next to you goes bankrupt, gets destroyed, or you buy them out, you get their land and you can expand
I'd be hooked on that sort of game for months
Will Wright games are always pretty ambitious. We'll have to wait and see how it turns out.
Edit: forgot link..... http://en.wikipedia.org/wiki/Cities_Unlimited
Edited by crashed97tsi - 12/14/08 at 10:51pm